For example, there is known in the art a feed system for a plasmarc furnace comprising an electrode and a gas conduit coaxially aligned with the electrode. The gas conduit is in the form of a hollow metal cylinder and the electrode is secured to its lower end. The plasmarc furnace feed system referred to above is likewise equipped with a means for the delivery of flux to the melting zone. The flux delivery may be carried out both intermittently and continuously. A fixing assembly for coupling the electrode to the gas conduit, which is made in the form of two connecting pieces and a clamping ring, is also included.
The aforesaid feed system enables gas and flux to be fed to the melting zone through the interior of the gas conduit and that of the electrode. Electric current is supplied to the electrode through the gas conduit.
However, the known feed system sulfers from substantial power losses due to the absence of reliable means for conducting electric current to the electrode. Since the gas conduit is not cooled, it wears out or becomes inoperative in a relatively short period of time due to the sharp drop in temperatures, namely: in the liquidus temperature during melting and the ambient temperature during the furnace charging.
The fixing assembly used for coupling the electrode to the gas conduit does not ensure tightly sealed connection between the electrode and the gas conduit, because of the fact that the components of the fixing assembly are heated in the course of melting.